Method and apparatus for parallel demodulation of high symbol rate data streams in a communications system

Abstract

A dynamic and flexible architecture and methods for demodulation of high data-rate streams with high symbol-rates, such as in satellite communications systems or computer network communications systems, is provided. A data stream of a data transmission is received, the data stream corresponding to a plurality of data symbols. A plurality of data samples corresponding to each of the data symbols is generated. Further, one or more representative data samples, corresponding each of the data symbols, are generated based at least in part on timing control signals and the generated data samples for the respective data symbol. The generated data samples corresponding to each of the data symbols other than the representative data samples are dropped. The timing control signals are then adjusted based at least in part on the generated representative data samples.

What is claimed is: 
     
       1. A method comprising:
 receiving a data stream of a data transmission, the data stream corresponding to a plurality of data symbols; 
 generating a plurality of intermediate data samples corresponding to each of the data symbols; 
 generating one or more representative data samples, corresponding to each of the data symbols, based at least in part on timing control signals and the intermediate data samples for the respective data symbol; 
 dropping certain of the representative data samples corresponding to each of the data symbols based on drop control signals; 
 generating error correction signals by determining phase errors corresponding to timing errors in processing the data samples, and filtering the phase errors; and 
 adjusting the timing control signals and the drop control signals based at least in part on the error correction signals. 
 
     
     
       2. A method according to  claim 1 , wherein the representative data samples comprise one or more of a fractional data sample and an integer data sample, and the timing control signals comprise one or more of a fractional time and an integer time. 
     
     
       3. A method according to  claim 1 , wherein the data stream is processed in a parallelized manner. 
     
     
       4. A method according to  claim 1 , wherein the data transmission comprises one of a continuous mode or a burst mode data transmission in a communications system, wherein the communications system comprises one or more of a satellite communications system and a computer network communications system. 
     
     
       5. A method according to  claim 1 , further comprising demodulating the data stream, wherein the demodulation of the data stream comprises:
 formatting the data samples into a parallelized format; and 
 generating the intermediate data samples at a sampling rate of at least approximately twice the symbol rate of the received data stream; and 
 wherein the generation of the representative data samples corresponding to each of the data symbols is performed based at least in part on a symbol timing recovery using a clock rate of a slower rate than the symbol rate of the data stream. 
 
     
     
       6. A method according to  claim 5 , wherein the representative data samples comprise one or more of a fractional data sample and an integer data sample, and the timing control signals comprise one or more of a fractional time and an integer time. 
     
     
       7. An apparatus comprising:
 at least one processor; and 
 at least one memory including computer program code for one or more programs, 
 the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to perform at least the following,
 receive a data stream of a data transmission, the data stream corresponding to a plurality of data symbols; 
 generate a plurality of intermediate data samples corresponding to each of the data symbols; 
 generate one or more representative data samples, corresponding to each of the data symbols, based at least in part on timing control signals and the intermediate data samples for the respective data symbol; 
 drop certain of the representative data samples corresponding to each of the data symbols based on drop control signals; 
 generate error correction signals by determining phase errors corresponding to timing errors in processing the data samples, and filtering the phase errors; and 
 adjust the timing control signals and the drop control signals based at least in part on the error correction signals. 
 
 
     
     
       8. An apparatus according to  claim 7 , wherein the data stream is processed in a parallelized manner. 
     
     
       9. An apparatus according to  claim 7 , wherein the data transmission comprises one of a continuous mode or a burst mode data transmission in a communications system, wherein the communications system comprises one or more of a satellite communications system and a computer network communications system. 
     
     
       10. An apparatus according to  claim 7 , wherein the apparatus is further caused to demodulate the data stream, wherein the demodulation of the data stream comprises:
 formatting the data samples into a parallelized format; and 
 processing the data samples at a sampling rate of at least approximately twice the symbol rate of the received data stream; and 
 wherein the generation of the representative data samples corresponding to each of the data symbols is performed based at least in part on a symbol timing recovery using a clock rate of a slower rate than the symbol rate of the data stream. 
 
     
     
       11. An apparatus comprising:
 a receiver module configured to receive a data stream of a data transmission, the data stream corresponding to a plurality of data symbols; 
 a sampler module configured to generate a plurality of intermediate data samples corresponding to each of the data symbols; 
 a control module configured to generate timing control signals and drop control signals; 
 an interpolator module configured to generate one or more representative data samples, corresponding to each of the data symbols, based at least in part on the timing control signals and the intermediate data samples for the respective data symbol; 
 a sample dropper module configured to drop certain of the representative data samples corresponding to each of the data symbols based on the drop control signals; 
 a filter configured to filter the representative data samples to provide one or more filtered data samples corresponding to each of the respective data symbols; 
 a phase detector configured to determine phase information regarding the filtered data samples; and 
 a loop filter configured to filter the phase information, and to generate filtered phase information signals, wherein the timing control signals and the drop control signals generated by the control module are based at least in part on the filtered phase information signals; and 
 wherein the control module is further configured to adjust the timing control signals and the drop control signals based on the filtered phase signals. 
 
     
     
       12. An apparatus according to  claim 11 , wherein the control module comprises:
 an oscillator configured to generate the timing control signals and the drop control signals, wherein the drop control signals are generated based at least in part on a ratio between an incoming symbol rate and an outgoing sample rate for the data stream. 
 
     
     
       13. An apparatus according to  claim 12 , wherein the representative data samples comprise one or more of a fractional data sample and an integer data sample, and the timing control signals comprise one or more of a fractional time and an integer time. 
     
     
       14. An apparatus according to  claim 12 , wherein the data transmission comprises one of a continuous mode or a burst mode data transmission in a communications system, wherein the communications system comprises one or more of a satellite communications system and a computer network communications system. 
     
     
       15. An apparatus according to  claim 12 , wherein
 the oscillator comprises a numerically controlled oscillator (NCO), 
 the interpolator module comprises one or more Lagrange interpolators; 
 the sample dropper module comprises one or more shift registers configured to provide the determined optimal representative data samples as output data samples for further processing, 
 the filter comprises a finite impulse response (FIR) matched filter, and 
 the loop filter runs at a rate of (symbol rate/N), where the “symbol rate” corresponds to the symbol rate for the received data stream and “N” corresponds to a number of the data symbols. 
 
     
     
       16. An apparatus according to  claim 15 , wherein the interpolator module determines the representative data samples corresponding to each of the data symbols through an interpolation operation based at least in part on two or more of the data samples for the respective data symbol and the timing control signals. 
     
     
       17. An apparatus according to  claim 11 , wherein the interpolator module determines the representative data samples corresponding to each of the data symbols through an interpolation operation based at least in part on two or more of the data samples for the respective data symbol and the timing control signals. 
     
     
       18. An apparatus according to  claim 11 , wherein the receiver module is further configured to format the received data symbols into a parallelized format. 
     
     
       19. An apparatus according to  claim 18 , wherein the data stream is processed at a sampling rate of at least approximately twice the symbol rate of the data stream, and generation of the representative data samples is performed based at least in part on a symbol timing recovery using a clock rate of a slower rate than the symbol rate of the data stream.